NASA's Curiosity rover measured a tenfold spike in methane, an organic chemical, in the atmosphere around it on planet Mars and detected other organic molecules in a rock-powder sample collected by its drill.
This temporary increase in methane - sharply up and then back down - tells us there must be some relatively localized source, according to Sushil Atreya of the University of Michigan, Ann Arbor, and Curiosity rover science team.
Methane, which is a simple organic molecule made of one carbon atom festooned by four hydrogen atoms, can be created in a number of ways. Bacteria make methane by combining hydrogen and carbon dioxide, and the energy liberated in the process powers their minute lives.
Chemical reactions between water and the minerals pyroxene and olivine in rock also release methane, as does the action of ultraviolet light from the sun on organic materials like comet dust and other meteoric material on Mars.
Whether manufactured through living or nonliving processes, methane generated underground can become trapped within the crystal structure of water to form a curious substance called clathrate, a form of methane ice.
Meteor impacts, cracks or faults in the Martian crust and simple outgassing can then release methane at a later date. Earth has abundant methane clathrates buried below deep ocean sediments and stored in permafrost. Methane is a powerful greenhouse gas that already plays a role in climate change and more of it isn't a good thing.
As Mars is a windy planet, any methane released is likely to thin out quickly and be scattered. Methane can be removed from the atmosphere through "photochemistry" or the sunlight's UV light sparking chemical reactions among molecules. These reactions can oxidize the methane, through intermediary chemicals such as methanol and formaldehyde, into carbon dioxide, the main ingredient in Mars' atmosphere.
The researchers utilized Curiosity's onboard Sample Analysis at Mars (SAM) laboratory a dozen times in a 20-month period to sniff methane in the atmosphere. During two of those months, in late 2013 and early 2014, four measurements averaged seven parts per billion. Before and after that, readings averaged only one-tenth that level.
Earth's atmosphere, of which methane is a minor constituent, averages 1,800 parts per billion. Cattle belching alone accounts for 1 percent of that total.
The rover also detected different Martian organic chemicals in powder drilled from a rock named Cumberland, the first clear detection of organics in surface materials of the Red Planet. These Martian organics could either have formed on Mars or been delivered to Mars by meteorites.
As we saw with methane, organic or carbon-containing materials aren't necessarily an indicator of little green bugs. They can form and be left in rocks through inorganic processes.
There is no way to know from the Curiosity data how they originated, but they do give us hope that Mars was once (and might still be) a planet favorable to life.
Identifying which specific Martian organics are in the rock is complicated by the presence of perchlorate minerals in Martian soils and rocks. Perchlorates are toxic salts used for propellants on earth because they have explosive properties. When heated inside SAM, the perchlorates change the structures of the organic compounds, masking the identities of the organics in the sample.
The rover also revealed interesting news about the past water in the Martian atmosphere. According to its measurements, the Cumberland rock formed 3.9 billion to 4.6 billion years ago and contains just half the ratio in water vapor in today's Martian atmosphere. This indicates that much of the planet's water loss occurred since that rock formed.
via Science - Google News http://news.google.com/news/url?sa=t&fd=R&ct2=in&usg=AFQjCNFGzvSlnytINR7QZDh9N17XUsPlQQ&clid=c3a7d30bb8a4878e06b80cf16b898331&cid=52778696965691&ei=LuihVKjyAajKwAGy3YGwCw&url=http://www.delhidailynews.com/news/What-caused-methane-spike-on-Mars-1419864933/
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